1. Field of the Invention
The present invention relates to a golf club head having face lines.
2. Description of the Related Art
Face lines are formed on many golf club heads. The face lines can contribute to increase in a backspin rate of a hitting ball. The face lines can suppress fluctuation in the backspin rate.
In golf in case of rain, a face impacts a ball with water present between the face and the ball. The water can reduce friction between the face and the ball. The face lines can suppress the influence of the water. In other words, the face lines can enhance spin performance in a wet condition.
In the case of shot from the rough, the face impacts the ball with grass (lawn grass) present between the face and the ball. The grass can reduce the friction between the face and the ball. The reduction in the friction may cause reduction in the backspin rate. A phenomenon in which the backspin rate is reduced is referred to as flier. The flier complicates the control of a flight distance. The face lines can contribute to the suppression of the flier. Since the grass is cut by the face lines, the flier can be suppressed.
On the other hand, the face lines may damage the ball. The damage includes also fine splitting. While the face lines having a sharp edge can contribute to increase in a spin rate, the face lines are apt to damage the ball.
Japanese Patent Application Laid-Open No. 2003-199851 (US2003/126734 A1) discloses a head having face lines with sharp edges, the head obtained by forming face lines in press processing, and carrying out cut processing of a face surface.
Japanese Patent Application Laid-Open No. 2008-36155 (US2008/032814 A1) discloses a golf club head having face lines having an edge to which a roundness having a radius of 0.2 mm or less is applied.
Japanese Patent Application Laid-Open No. 2007-7181 discloses an iron golf club set including a sand wedge and the other clubs, a curvature radius of an edge of a face line of the sand wedge being different from those of the other clubs.
Japanese Patent Application Laid-Open No. 2008-206984 (US2007/0149312 A1) discloses a shape of a face line capable of increasing a backspin rate.